A labour hire company that recruits Pacific workers for the Seasonal Worker Program has been suspended from further recruitment by an Australian government department, amid an investigation into allegations that Vanuatu workers were underpaid at a farm in Victoria.

Meanwhile, the head of Vanuatu's National Workers Union says he's disappointed by the allegations, which were first reported by Australian media at the weekend, and also make claims that workers were exposed to dangerous working conditions and threats.

The managing director of the hire company has denied all the claims, as has the farm.

And while official investigations continue, the workers at the centre of the allegations are set to arrive back in Vanuatu today.